He said Democrats will be seeking more GOP support when Congress returns to Washington next week after the weeklong President's Day recess.

"This isn't a situation where we've just been courting one side," Castro said.

Pelosi, who has sent letters to Republicans seeking their support, extended that invitation again Friday.

"I know they care about the Constitution of the United States; I know they care about the separation of powers and the coequal nature of the branches of government," she said. "What's really important is how they will vote on Tuesday."

Republicans, however, appear ready to oppose the resolution in overwhelming numbers. Despite some public GOP criticisms of the emergency declaration — particularly Trump's plan to shift $3.6 billion away from military construction projects around the country — Republican lawmakers have little incentive to buck their White House ally on his signature issue of border security.

Trump's declaration arrived last Friday, after Congress denied his request for $5.7 billion in new border wall funding in an enormous spending package. Trump signed the bill, which prevented a second government shutdown, but only reluctantly. His emergency declaration was an end-run around Congress to secure the funding for the "big beautiful" wall he'd promised during the 2016 campaign.

Castro, the chairman of the Congressional Hispanic Caucus, said Trump's declaration — which the president argues is necessary to protect national security from what he has described as waves of migrants arriving at the southern border — is based on a false pretext.

"There is no emergency at the border," Castro said.

Pelosi piled on, saying Trump is acting, not because there's a true national emergency, but "to honor an applause line at a rally."

"Does the president have the right to do such a thing when there is a true emergency? Yes, he does. And if there is such an emergency ... we'd be right there with him," she said. "This is not what is happening now."

The resolution will go to the House Rules Committee on Monday, and then to the floor on Tuesday.

The resolution is "privileged," which means it's guaranteed a vote in the GOP-controlled Senate, where it would require a simple majority to pass.

Pelosi noted that the expedited nature of the resolution likely means the Senate will take up the House version without changes.

"We do not anticipate that there will be any amendments to it," she said.

If the resolution were to reach Trump's desk, the president has promised to veto it. Neither chamber is expected to have the two-thirds support to override that veto.

A number of states and outside groups have already sued the administration to block the emergency declaration. Pelosi on Friday declined to say how House Democrats will approach the court battle, either by filing a separate suit or piling on to an existing one.